Keyhole-guard



(No Model.)

0. J.D'A-'VIDSON. KEYHOLE GUARD.

No. 511,592. Patented Dec. 26, 1893' v INVENTOH WITNESSES:

- ATTORNEYS.

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" NITED STATES PATENT OFFICE.

OSCAR J. DAVIDSON, OF KINGSBURG, CALIFORNIA.

KEYHOLE-GUARD.

SPECIFICATION forming part of Letters Patent No. 511,592, dated December26, 1893.

V Application filed Pelmiary 25, 1893 Serial No. 463,670. (lll'o model.)

hole guard which is simple and durable in.

construction, and arranged to close the keyhole whenever the bolt isshot out.

The invention consists of certain parts and details, and combinations ofthe same, as will be hereinafter described and then pointed out in theclaims.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar letters of reference indicatecorresponding parts in all the figures.

Figure l is a sectional side elevation of the improvement as applied onan ordinarydoor lock, the section being taken on the line 11 of Fig. 3.Fig. 2 is a front view of the same. Fig. 3 is a sectional plan view ofthe same on the line 33 of Fig. 1. Fig.4 is a transverse section of thesame on the line 4-4 of Fig. 1; and Fig. 5 is a perspective View of thesame.

The look A, on which the improvement is applied, is provided with theusual casing B, containing the bolt 0, adapted to be shot out or movedin, in the usual manner, by the key D inserted into thelock casingthrough either of the keyholes in the back plate B, or the cover B ofthe casing B. In the back plate B and cover B are arrangedlongitudinallyextending guideways B and B respectively, in which arefitted toslide longitudinally, the keyhole plates E and E respectivelyeach provided with a keyhole E adapted to register with thecorresponding keyhole in the respective back plate B or cover B Thekeyhole plates E and E are provided with forwardly-extending springextensions E and E respectively, each curved inwardly to engage oppositesides of the bolt 0, the extensions being provided near their free endson top with notches E and E adapted to be engaged by lugs O and Crespectively, projecting from opposite sides of the bolt 0.

In order to hold either or both of the two extensions E or E out ofcontact with the respective side of the bolt C and the correspondinglugO or 0 ,1 provide a cam F secured on a longitudinally-extending rod Gmounted to turn at its inner end in a bearing I-I secured to the casingB, the outer end of the said rod being journaledin thefront plate B ofthe lock casingB. On the front end of therod G is arranged a handle Gfor convenientlyturning the rod G so as to move the cam F in contactwith either or both of the spring extensions E and E to press the sameoutward out of engagement with the corresponding lug C or C of the bolt0. The handle end G ofthe rod G is arranged in a recess B formed in thefront plate of the door lock casing so as to present no obstruction onthe said front plate B When the handle Gis in the position as shown inthe drawings, then the cam F presses the extension E to hold the notch Ethereof out of engagement with the lug O of the bolt C. The other springextension E is disengaged by the can] F and has its notch E inengagement with the lug O, as will be readily .understood by referenceto Fig. 3. In this case, the keyhole plate E is inactive and its keyholeregisters with the keyhole in the cover B while the other keyhole plateE is active whenever the bolt (He shot out or in, as the extension E ofthe said plate E is engaged by the lug O.

Now, it will be seen that'when the bolt 0 is in an innermost position,the keyhole E of the guard plate E registers with the keyhole in theback plate B, and when the key D is inserted through the keyhole in thecover B and the bolt 0 is shot out by the key D, then the guard plate Emoves withthe bolt 0, thus moving its keyhole E out of register with thekeyhole in the back plate B, thus closing the latter and preventing theinsertion of a key from that side of the lock. When the bolt 0 is movedinward by the keyD, then the guard plate E moves with it, to again bringits aperture E to register with the keyhole in the back plate B. Now,when it is desired to close the keyhole in the cover plate B then theoperator turns the handle G into the position shown in dotted lines inFig. 2, whereby the rod G is turned, and the cam F moves out of contactwith the spring extension E and in contact with the spring exten sion Ethus pressing the latter out of engagement with the bolt 0, andpermitting the other extension E to engage with its notch E, the lug Oof the bolt. WVhen the key D is inserted through the keyhole in the backplate B to move the bolt 0 outward, then the guard plate E moves withthe bolt, thus closing the keyhole in the cover B Thus, it will peringwith the handle when the door is closed. Having thus fully described myinvention,

I claimas new and desire to secure by Letters Patent-- 1. A keyholeguard, comprising two plates fitted to slide in the lock andengaging oppositesides of the bolt so as to be moved thereby, and meansfor disengaging one or both of the plates from the bolt, substantiallyas described.

2. A keyhole guard comprising a guard plate fitted to slide in the doorlock casing and provided with a spring extension adapted to be engagedby the lock bolt and means for The recess B is preferably a half circlehaving the edges of the front plate full so that there can be nopossible tam-.

disengaging the spring extension from the bolt, substantially as shownand described.

3. In a keyhole guard, the combination with a lock having its boltprovided with projecting lugs, of plates fitted to slide in the lockcase and each having a spring extension provided with a notch adapted toengage the lugs of the bolt, and means for disengaging one or both ofthe plates from the bolt,substantially as described.

at. The combination with a door lock bolt provided with lugs, of keyholeguard plates fitted to slide in the door lock casing and provided withspring extensions having notches adapted to be engaged by the said boltlugs, and a cam for holding one or'both of the said spring extensionsout of contact with theilug, and permitting the other extension to movein engagement with its lug, substantially as shown and described.

5. The combination with a door lock bolt provided with lugs, of keyholeguardplates fitted to slide in the door lock casing and provided withspringextensions having notches adapted to be engaged by the said boltlugs,

a cam for holding one of the said spring extensions out ofcontact withthe lug, andpermitting the other extensionto move in engagement with itslug, and a rod mounted to turn in the casing and carryingthe said-cam,substantially as shown and described.

OSCAR J. DAVIDSON. Vitnesses:

F. D. RosENDAM, E. A. DAVIDSON.

